This invention relates to vacuum contactors and more particularly to a mechanical interlock for vacuum contactors which insures operation of only one of two contactors at a time.
Vacuum contactors are compact electrical devices which can open and close circuits quite effectively and efficiently. Since the electrical contacting parts are enclosed in a vacuum, there are no visible arcing parts which is desirable in many environments. In some applications, two vacuum contactors are employed with one closed to serve a particular function while the other one is open and vice versa. In these applications, it is not desirable to close both vaccum contactors simultaneously. It is possible to monitor the condition of a vacuum contactor to be informed of whether the contactor is open or closed; however, in some applications, it is not sufficient to merely know whether a contactor is open or closed. In some instances, one of the contactors must be prevented from opening or closing depending upon the condition of the other contactor. While operating conditions can be monitored, it is simply insufficient to known the operating condition of one vacuum contactor when one must be controllable in response to the operating condition of the other.
One of the problems with vacuum contactors is that their moving components are sealed inside the vacuum bottle. However, there is a small amount of detectable movement when the vacuum bottles are mounted in an environment such as in a motor controller. Even though it is known that a small amount of movement exists, there is no practical way to utilize this movement to achieve the result which is desired of preventing operation of one vacuum contact depending upon the condition of the other vacuum contactor. Accordingly, it will be appreciated that it would be highly desirable to have a device which would prevent operation of the second vacuum contactor when the first vacuum contactor is closed and to prevent closing of the first vacuum contactor when the second contactor is already closed.
Accordingly, it is an object of the present invention to provide a mechanical interlock device which blocks closing of one vacuum contactor as soon as the other vacuum contactor closes.
Another object of the present invention is to provide a mechanical interlock which achieves the interlock function by using the small limited movement of the vacuum contactor. Another object of the present invention is to provide a mechanical interlock which is simple to manufacture and use.